Tesla and Panasonic are deepening their partnership with a three-year battery-pricing deal.

Disclosed in a Tesla filing Tuesday, and first spotted by Reuters, the deal sets terms for production capacity commitments by Panasonic at the jointly-operated Nevada Gigafactory, as well as purchase volume commitments by Tesla over the first two years of the agreement.

Signed last week and effective April 1, 2020, the battery-pricing deal also amends the general terms and conditions of the partnership between Tesla and Panasonic, modifying the term to expire 10 years after Panasonic achieves certain manufacturing milestones, Reuters reported.

Tesla and Panasonic have also reportedly been in talks to expand the Gigafactory, which has become somewhat of a sticking point for the two companies.

Tesla gigafactory, March 2016, shown in drone footage posted to YouTube by Above Reno

Last year, Panasonic CEO Kazuhiro Tsuga indicated that Tesla Model Y production could strain battery supplies. A month prior to that, Tesla CEO Elon Musk tweeted that Panasonic's battery-production rate had restricted Model 3 production.

Battery cells produced at the Gigafactory were expected to start turning a profit for Panasonic sometime during the ramp-up of Model 3 production.

More recently, Tesla has turned to CATL for some cell supply in China, although it has no large-scale deal with CATL as it does with Panasonic. CATL currently supplies cells for Tesla electric cars built in China for local sale.

Meanwhile, Toyota and Panasonic have continued to leave the door open for a large-scale supply agreement around EVs. Last year, Toyota reportedly started using Panasonic-supplied cylindrical battery cells in some Chinese-market plug-in hybrids, in place of the prismatic cells used in other markets.